ABSTRACT
The idea of emergence arose in philosophy to characterise a compromise between monism and dualism in different areas. The rough idea is that certain novel and initially unexpected properties of complex systems such as organisms and persons are unpredicted, unexplained, or irreducible on the basis of the simpler parts of those systems. From there, as engineered systems became more complex, the notion spread to engineering. Neither philosophers nor engineers are close to agreement on what emergence is, so the principal task of this contribution is to distinguish the various meanings and determine which may be useful for engineering. There is no single concept of emergence, but several more specific notions can be of use in current and future application.
